The present invention relates to air conduit structures suitable for use with, for example, an upright vacuum cleaner.
Vacuum cleaners are common and well-established appliances for commercial and residential floor care. A wide variety of vacuum cleaner configurations are available to suit the needs of a particular application or user, including upright vacuums, canister models, and hand-held models.
Vacuum cleaners, such as upright vacuums, remove dirt from a carpet by creating a suction strong enough to draw the dirt particles and other contaminants from a section of the carpet up into the vacuum cleaner where the dirty-air is passed through a vacuum bag in which the entrained dirt is captured. To increase the efficiency of this process, a base portion of the vacuum cleaner often has a roller brush for agitating dirt from the carpet as it is being vacuumed.
Inside the vacuum cleaner, a conduit transfers the dirty air from the base of the vacuum cleaner to the vacuum bag. The dirty air conduit runs up a handle assembly or, in cases where the dirty air conduit is rigid, the dirty air conduit can itself function as a portion of the handle. At the end of the dirty air conduit opposite the floor there is a duct from which the dirty air exits from the dirty air conduit. The vacuum bag is attached to the dirty air outlet nozzle and receives and filters the dirty air which it receives from the duct.
The vacuum bag has a bag opening that fits closely over the dirty air outlet duct. The vacuum bag is otherwise a completely closed bag that is made from a porous material, such as porous paper, that allows air to flow through it, but which is too fine for most dirt particles to pass through. As dirty air passes through the vacuum bag, the air is forced through the porous material and the dirt is trapped in the bag. The bag thus collects the dirt from the dirty air and, more importantly, from the floor. Because the material of the vacuum bag is often fragile and can get very dusty, the vacuum bag is commonly held within a protective outer bag.
One common vacuum bag design incorporates a reinforced area, known as a collar, surrounding the bag opening. The collar is usually a square or rectangular piece of thin cardboard. To install the vacuum bag, the user holds the collar by one or more edges, and forces the bag opening over the dirty air outlet nozzle. The collar can be designed with an elastic seal extending inward from the circumference of the bag opening to further seal the gap between the dirty air outlet duct and the bag opening.
As shown in FIG. 1, a prior-art upright vacuum cleaner 20 may comprise a head 22, which includes a motor and fan which cooperate to create suction at floor level. Air sucked into the head 22 by the fan is blown into the dirty air conduit 24 that forms a part of the handle 26 of the vacuum cleaner. Upon reaching the end of the dirty air conduit 24, the air stream with its entrained particulates (the dirty air) is directed through the dirty air exhaust duct 28 into a flexible vacuum cleaner bag 30, which is mounted in a generally air-tight manner to the exhaust duct 28.
FIG. 1 also provides an exploded view of a prior-art dirty air exhaust duct 28 docking system 32 for receiving air from a dirty air conduit and diverting it laterally into a vacuum cleaner bag 30. The docking system 32 comprises a yoke 34 which may be mounted about the periphery of the exhaust duct 28. The exhaust duct 28 includes a flange (not shown) about its periphery for retaining the yoke 34 in place.
The yoke 34 is hinged to a bag dock 36 into which the mounting collar 38 of the bag 30 may be inserted. The yoke 34 and bag dock 36 are made of a somewhat rigid plastic material and snap together when they are pivoted relative to one another from the open position (shown in FIG. 1) to a closed position.
A mounting collar 38 is mounted on the vacuum cleaner bag 30. This collar is configured to slide into guides on the bag dock 36. The mounting collar 38 includes a flexible seal 40 which covers a portion of the aperture 42 which extends through the mounting collar 38 and opens into the interior of the bag 30. The collar 38 is made of three layers of cardboard or the like, the middle layer being slidable with respect to the front and back layers. The tab 44 forms a lower portion of the middle layer of the collar 44, and may be pulled downward relative to the collar 38 to slide the middle layer to a position where the aperture 42 is covered. In this position, the particulate material in the vacuum cleaner bag 30 is sealed therein.
When the bag dock 36 is pivoted to its closed position relative to the yoke 34, the aperture 42 and the seal 40 are positioned about the periphery of the exhaust duct 28 in sealing engagement therewith. The exhaust duct 28 is then in communication with the interior of the vacuum cleaner bag.
In prior art upright vacuum cleaners, such as that shown in FIG. 1, the dirty air conduit 24 generally is closed off adjacent to the dirty air exhaust duct 28 to which the vacuum bag is attached. This exhaust duct generally extends at right angles from the upper end of the dirty air conduit a sufficient distance so that the vacuum cleaner bag, and, as applicable, an outer bag made of cloth or the like, can be mounted on it, with the open mouth of the duct exhausting the dirty air into the bag.
While such a vacuum cleaner functions adequately, there remain certain problems with the design. A common complaint relating to this and other vacuum cleaners is that they are very noisy. One component of this noise is believed to be caused by turbulence generated as the rapidly-flowing dirty air reaches the upper, sealed end of the dirty air conduit and flows laterally out the dirty air duct.
Another difficulty of the present design is rebounding of larger, heavier objects, such as coins, after impact with the sealed end of the conduit. Since the sealed end of the dirty air conduit is generally perpendicular to the direction of flow of the air up the conduit, such objects may bounce back down the conduit (against the air flow) only to be blown back into the end of the conduit and rebound again. Eventually, the object may be blown into the bag, ending this cycle of rebounding, but the noise of the impacts of such objects into the sealed end of the conduit can be disconcerting to users of the vacuum cleaner.
The design also results in loss of vacuum cleaner efficiency. The abrupt change in airflow direction and the turbulence generated in the course of such change of direction result in greater backpressure in the conduit, which results in a reduction in cleaning ability of the vacuum cleaner.
The present invention is directed to a dirty air exhaust duct for a vacuum cleaner. The exhaust duct receives air from a dirty air conduit and directs it into a vacuum cleaner bag. A vacuum cleaner bag may be mounted to the exhaust duct to collect dirt in the dirty air. A deflector may be mounted on the exhaust duct to prevent air exiting the exhaust duct from blowing directly against the opposed inner wall of a bag mounted to the exhaust duct.